University of Illinois

No. 11/June 5, 1998

Stalk Borerers Are Ravaging
Some Fields, Too

Apparently stalk borer larvae are making their presence known in Illinois. Ron Hines, senior research specialist at the Dixon Springs Agricultural Center in southern Illinois, stated that he has seen more injury caused by stalk borers this year than ever before. John Shaw, coordinator of the Insect Management and Insecticide Evaluation Program with the Illinois Natural History Survey, also has found stalk borers with relative ease. If you haven't begun to look for these pests, don't delay much longer.

We have discussed stalk borers thoroughly in two previous issues of this Bulletin (no. 8 and 10, May 15 and May 29), providing information about heat units, thresholds, and management. The most important thing to remember at this time of year is that stalk borers embedded deeply in reasonably large plants (7- to 8-leaf stage) cannot be controlled with insecticides. If stalkborer larvae are killing very small plants, control might be justified as the larvae move from dead plants to healthy plants to continue their development. Refer to issue no. 10 (May 29, 1998) for insecticide recommendations.

Kevin Steffey (, Extension Entomology, (217)333-6652